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| From | "Martin Weiss" <martin.weiss1@gmx.de> |
| To | <statalist@hsphsun2.harvard.edu> |
| Subject | st: RE: First visit to clinic |
| Date | Mon, 20 Sep 2010 15:29:47 +0200 |
<> ************* bys id (date): ************* HTH Martin -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Paul O'Brien Sent: Montag, 20. September 2010 15:25 To: statalist Subject: st: First visit to clinic i want to create a new variable with the date of the first visit of each patient: id date date_of_first_visit N-00-3558 07/04/2008 07/04/2008 N-00-3558 09/04/2008 07/04/2008 N-00-3558 14/05/2008 07/04/2008 N-00-3563 05/06/2007 N-00-3563 31/03/2010 N-00-3565 05/06/2007 N-00-3565 13/06/2008 N-00-3565 13/06/2008 N-00-3565 05/05/2009 N-00-3565 04/03/2010 N-00-3583 09/09/2008 N-00-3583 27/05/2009 i know this should be easy by i am having trouble using n_1 i have tried: .sort date .by id, sort: gen visit=_n==1 but the latter does not have the date in order, only id. any help gratefully received. paul ------------------------------ Dr Paul O'Brien Raymede Clinic Westside Contraceptive Services Central London Community Healthcare Exmoor St London W10 6DZ UK +44 (0)20 8962 4450 * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/